1. Field of the Invention
The present invention relates to novel adamantane derivatives having an adamantane skeleton which are excellent in optical properties, heat resistance, acid-dissociating property, etc., and useful as crosslinking-type resins, optical materials such as optical fibers, light wave guides and photoresists and raw materials thereof, intermediate products of medicines and agricultural chemicals, or various other industrial products.
In addition, the invention relates to functional resin compositions that are usable as raw resist materials for KrF, ArF or F2 excimer laser, or chemically-amplified type resists for X-rays, electron beams or EUV (extreme ultraviolet rays), as well as acrylate compounds having an adamantane skeleton which are used as raw materials of the compositions.
2. Description of the Related Arts
It is known that since adamantane has a rigid structure and a high symmetry, and derivatives thereof exhibit specific functions, these compounds are useful as high-functional resin materials, intermediate products of medicines, and optical materials (refer to Japanese Patent Publication No. Hei 1(1989)-53633 and Japanese Patent Application Laid-open No. Hei 6(1994)-305044) as well as photoresists (refer to Japanese Patent Application Laid-open No. Hei 4(1992)-39665).
On the other hand, the functional resin compositions used as a resist in semiconductor production processes are required to have well-balanced properties including an ability of rendering light-irradiated portions thereof alkali-soluble, etching resistance, adhesion to substrate and transparency to light irradiated from a light source. As the resist suitable for KrF excimer laser or a light source with a shorter emission wavelength than that of the KrF excimer laser, there are generally known chemically-amplified type resists. The chemically-amplified type resists are usually used in the form of a solution containing the functional resin composition as a main component as well as a photo-acid generator and several kinds of other additives. It is important that among these components, the functional resin composition as a main component exhibits the above respective properties in a well-balanced manner since a performance of the resist is determined by these properties.
In the chemically-amplified type resists for KrF excimer laser or a light source with a shorter emission wavelength than that of the KrF excimer laser, the functional resin composition as a main component thereof generally comprises a polymer containing repeating units such as acrylates. However, the polymer is not composed of a single kind of repeating unit. The reason therefor is that the composition containing a polymer composed of a single kind of repeating unit is incapable of satisfying all of the above properties such as etching resistance. In fact, plural kinds, i.e., two or more kinds of repeating units having functional groups for improving the respective properties are used in the form of a copolymer in the functional resin composition. As resins contained in the resist composition, there have been proposed hydroxystyrene-based resins for resists used in KrF excimer laser lithography, and acrylic resins containing 2-alkyl-2-adamantyl methacrylate as a basic skeleton for resists used in ArF excimer laser lithography (refer to Japanese Patent Application Laid-open Nos. Hei 4(1992)-39665 and Hei 10(1998)-319595).
In recent years, fine processing techniques in lithographic processes have rapidly proceeded. In particular, light sources used in the processes are required to enable formation of images with a line width as narrow as about one-third of a wavelength of light emitted therefrom. With narrowness of the line width, it has been more strictly required to improve resolution and ling edge roughness. One of the reasons therefor is non-uniformity of the functional resin composition due to large difference between properties of the respective repeating units contained therein (refer to “SEMICON JAPAN SEMI Technology Symposium 2002”, 3-27). Further, there have been proposed resist compositions containing an adamantanecarboxylic acid derivative which are alkali-soluble and have a good etching resistance (refer to Japanese Patent Application Laid-open No. 2000-122295). Also, there have been proposed resist compositions having a low surface roughness and a low line edge roughness upon etching which comprise a copolymer whose main chain is composed of an acrylic ester derivative, as a single kind of repeating unit, containing as its basic skeleton an acrylate such as typically 2-(1-adamantyl)-2-methacryloyloxypropane (refer to Japanese Patent Application Laid-open No. 2003-167346).
However, in many cases, the repeating units contained in these compositions satisfy only one or two of the properties required for the chemically-amplified type resists such as etching resistance, alkali developability and adhesion to substrate. Therefore, in order to meet the above strict requirements, 3 or 4 kinds of repeating units must be contained in the compositions, and the number of the repeating units to be contained in the compositions tends to increase more and more. For this reason, it becomes more difficult to allow the compositions to have a good uniformity and therefore sufficiently meet the requirements concerning resolution and line edge roughness thereof.
Under these circumstances, it has been strongly demanded to develop functional resin compositions that are free from adverse influences on basic properties thereof, and excellent in alkali developability and adhesion to substrate so as to improve resolution and line edge roughness thereof.